2009-06-29

Hard disk are getting bigger and bigger. Network interface card (NIC) and switch are getting cheaper and cheaper. It usually means more services can squeeze into a server. Combining multiple network interface into 1 big pipe would be a big plus for services that is bandwidth hungry. e.g. file server, email server & etc

Combining 2 or more network interface have a few advantages. One of them is load balancing. Load balancing enables the network interface card to share the load among the 2 or more network interface card defined. It serves as redundancy as well. But load balancing does not makes full use of the 2 or more network interface, it is meant to share network traffic load.

To fully utilize 2 or more network interface links, link aggregation should be used. Link aggregation is a method to combine 2 or more network interface to become a bigger pipe. It is also a way to combine 2 or more interface to use the same IP address. Using link aggregation can also create redundancy, if one of the link fails, the other links will take over.

This post is using FreeBSD as a server because FreeBSD have all the ports (software packages) you will need and server administration on it is made to ease systems administration daily task.Without further ado, below are the steps to configure 2 (or more) network interfaces to work as 1 big trunk or round robin :

2009-06-27

Storage are getting cheaper and cheaper. Almost a year ago, a 250 GB 2.5" portable hard disk would cost 120 bucks. But now, it only cost 100 bucks for a 500 GB hard disk. Size are getting bigger and bigger with the same monetary value but does the hard disk spins fast enough to fetch the big "gigabytes" in time? Of cause, given "enough" time, any rate of spin could fetch any size of data. Files are getting larger and larger, especially audio & video files. Fetching the files in an reasonable time is crucial.

Before we proceed to check out the command on how to check hard disk transfer speed or read timings, we will need to familiarize our self with hard disk naming convention. Here is a simple guide on how to identify hard disk naming convention in /dev (where device node are store) :

2009-06-26

Firefox have all the bells & whistles to make our internet life happy. Tabs, plugins, portability and keyboard shortcuts. Firefox keyboard shortcuts make browsing addictive, especially to system administrator, which our hands are on the keyboard most of the time. We could use mouse to browse it but wouldn't you think by keeping your hands on the keyboard would increase productivity? :)

Below are the list of keyboard shortcuts plus a few combination of mouse clicks which commonly used in Firefox. There are of cause other shortcuts available but this post only attempt to introduce you with the efficiency of using keyboard shortcuts (almost mouse-less) rather then trying to exhaust your brain memory in crunching the full list of keyboard shortcuts. You can print the below list of Firefox keyboard shortcut keys out and act as a Cheat Sheet. It can be useful in getting familiar initially using the keyboard shortcut keys. Here are the list :

2009-06-23

This common error happens normally after a WordPress version upgrade. Upon upgrade of plugins, which normally we click on the "upgrade automatically" link on the plugins page, it prompt for "connection information" (with another line of "To performed the requested action, connection information is required.") with "hostname", "username", "password" & "Connection Type" required.

This issue is caused by certain wordpress essentials files or directory are not accessible by WordPress.

2009-06-21

PostgreSQL is an open source RDBMS (Relational DataBase Management System) that is not only feature rich, fast and light but also easy to use. Its documentation available at its website is a superb way of learning as well. Browsing the documentation and you will find that its way of explaining is no "bullshit" approach, short and concise.

After the initial installation, one might forget to set the password after running the initial script to setup the database. After a while, naturally, we all forget the password. Below are the steps to reset the password for user name "postgres" :

The Nokia E71 & E63 is a versatile phone for people that needs the business suite of application, e.g. email, messenger, documents & spreadsheet, camera and most importantly, the symbian platform. The symbian platform is widely used on mobile phones. Symbian's platform also have a wide variety of applications.

For *NIX system administration, shell access to the command line (using ssh) of the servers are part of our life. Having to own Nokia E71 or E63 is one of the best thing as Putty is available on symbian platform. Putty is a symbian application that can connect to server using shell access or command line by ssh, which take advantage of the built-in QWERTY keyboard on Nokia E71 & E63. Putty also allow to use public key authentication, if the private key is installed on the phone or the memory card (mmc). It also allow to configure ssh (secure shell) client to connect to other ports then the default port 22.

2009-06-19

After an upgrade of Nagios, Nagios re-schedule function for next service check is not working. The Nagios web interface complained "Error: Could not open command file '/var/spool/nagios/rw/nagios.cmd' for update". Its problem lies on the webserver was unable to access the file to update the schedule.

2009-06-18

The usual root account are meant for critical task, such as single user mode related operation. It hails the power of the system, as well the power of destruction (try "rm -rf /" :p). That's the reason why a lot of company have a policy to seal the root account or make some red tape so that one will give up requesting to use it. But sealing the root account will make daily routine system administration task difficult to execute.

No worries, sudo is the tool to clone another account with root privilege or control the access of critical command of a linux or BSD box. Every command that runs through sudo will be log to /var/log/auth.log.

2009-06-17

WordPress 2.8 is available for upgrade from either the Dashboard (by 1 click upgrade) or manually download it from wordpress.org and install it through command line. If you are using the first option, which upgrade through the Dashboard, you might noticed that after the upgrade, the Visual Editor might stop working or the tool bar is missing from the Visual Editor. Google it will bring you to wordpress.org and recommand you to do some tedious troubleshooting steps.

This blog have just upgraded and encounter the same problem. After following the recommendations, step 3 of it works, which is removing the current wp-includes and wp-admin folder then replace it with the latest version of it by downloading latest.tar.gz from wordpress.org and extract from it.